Lean on Initial Setup for creating a new user?

Would it be possible/make sense to lean on Initial Setup for creating new users? Whether that means opening Initial Setup in the current user session, or somehow opening the greeter in an Initial Setup context.

I feel like that'd be nice so that we don't have to try to keep this workflow in sync, and automatically get new features like https://github.com/elementary/initial-setup/pull/84.

The issue mentions the current new-user workflow and the Initial Setup project, but names no files, tests, or entry points. First determine how new users are currently created and how Initial Setup is launched; done would require an agreed integration approach, which this issue does not define.

Written by the indexing model from the issue text.